U.S. Pat. No. 4,648,840 discloses a dental handpiece of the before mentioned kind which is provided at a backward end of a gripping sleeve or handle with an integrated powder container. This powder container stores a predetermined amount of powder as an abrasive material for the polishing or cleaning of teeth in the course of a singular treatment of teeth. The powder container is designed as a cylindrical pot or cannister the axis of which extends downwardly and substantially perpendicular to the axis of the gripping sleeve. This cylindrical cannister is provided on its open end with a screw connection for its connection with the gripping sleeve. The gripping sleeve is provided at this screw connection with the inlet end of a flow line for pressurized air and at a directly adjacent position with the outlet end of a transfer line for powder mixed with air. Both of these inlet and outlet ends are formed as connection bores of the respective flow and transfer lines whereby their axis extending in parallel to each other are both directed towards the bottom of the cannister. The powder and air mixture which is formed in the powder container is transferred via the transfer line to a multiple nozzle arrangement of a forward spray head of the handpiece. A supply line for water is also connected with this nozzle arrangement so that at the time of a tooth treatment a common delivery of the powder and air mixture together with water may be obtained. Supply of pressurized air in common with supply of water is obtained at the backward end of the gripping sleeve via a turbine in-line quick coupling of a supply connection for air and water of a standard dental unit as generally available in any dentist's office.
With the particular design of the powder container as a cylindrical cannister and further with the particular design of its connecting bores connected to the flow line for pressurized air and to the transfer line for powder mixed with air respectively there may be caused unfavorable mixing conditions within the powder container at the time of an actual tooth treatment. For avoiding any unnecessary disadvantages of the prophylaxis treatment the known handpiece therefore requires some increased skill of the dentist for his handling of such a handpiece whereby he also has to consider different specific gravity characteristics of the handpiece due to the arrangement of the powder container directly adjacent its turbine in-line quick coupling of the supply connection for air and water since such additional equipment is missing in other similar add-on dental instruments.